In this study, isoflavone (genistein, genistin, daidzein, daidzin) contents in various parts of twelve soybean cultivars and three soy sprouts were determined by high performance liquid chromatography with UV detector. Three cultivars of soybean were selected and cultured in the lab to produce sprout for five days. Total isoflavone (Total IF) varied greatly among differnt breeds of soybean in range of 99 - 649.9 $mu extrm{g}$/g and 522.3 - 1,277.7 $mu extrm{g}$/g respectively, domestic and foreign cultivars. There were greatly difference in total IF of various parts of the soybean sprouts. Sprout from the Myunjunamul-kong appeared to have 69% genistein and 22% genistin in head part, and 30% and 62% of daidzin and daidzein, respectively, in root. Meanwhile, the sprouts from Junjori contains most (84%) of daidzein in its root. Sprout from chinese black-soybean had the largest amount of genistein among the sprouts but, there were no differences in the average genistein content between three selected black and non-black soys. The glycosidic form of IF were dominant compared to aglycone forms both in soybean and sprouts by 24 times and 12 times, respectively, suggesting that during the sprouts cultivation glycosidic forms could change to aglycone forms. There are no difference in total content between genistein + genistin and daidzein + daidzin in soy and soy sprout. Therfore, considering the total IF contents, the intake of 1 soy sprout is similer to 1.5 times as soybean.